1. Field of the Invention
The present invention relates to image forming apparatuses and memory control methods.
2. Description of the Related Art
Conventionally, there were demands to print a large image such as a design drawing, a blue print or a poster having a large impact. But recently, there are also demands to improve the picture quality (or image quality). Hence, the picture quality obtained by a printer which prints the large image must not be deteriorated compared to the picture quality obtainable by the popularly used printers which can print on a medium having a size of up to A3 size, for example. In addition, there are market demands to use color printers.
On the other hand, a Japanese Patent No. 3730586 proposed a mechanism that enables an engine to directly write image data to a memory.
According to this proposed mechanism, two toggle buffers are used to alternately input the image data, to form an image forming apparatus (or a MFP: Multi-Function Peripheral) which inputs the image data using a small amount of memory space.
Furthermore, because the circuit scale and the development cost increase when the conventional Application Specific Integrated Circuit (ASIC) input system is employed for the color printing, there are demands to realize a mechanism which enables the engine to directly write the color image data to the memory.
However, in the case of the image data related to a long image, a large amount of image data is repeatedly input to the memory, and the input image data needs to be backed up (or saved) in a Hard Disk Drive (HDD) or the like at all times. In the case of a monochromatic image data, there only are one input path and one backup path, and the timings need only be adjusted between the two paths. However, in the case of the color image data, there are a plurality of input paths for the cyan (C), magenta (M), yellow (Y) and black (K) image data or, red (R), green (G) and blue (B) image data, while there is only one backup path. For this reason, the color image data cannot be backed up efficiently by merely adjusting the timings between the backup path and the plurality of input paths.
In addition, when the engine repeatedly writes the image data to the memory, the mere use of the two toggle buffers as in the case of the proposed mechanism described above cannot flexibly cope with general applications.